Through the years there have been numerous systems developed for the collection of blood samples. The most common method today is the use of a double ended needle in combination with an evacuated tube and a holder for guiding the needle and tube into coupling relationship. The basic system is described in U.S. Pat. No. 2,460,641 and initiated a new technique for collecting blood samples and one which to a large extent has replaced the traditional method of collecting each blood sample in a separate syringe.
The system is now well known and utilizes basically a three part arrangement with many variations having been developed over the years to improve each of the three basic components.
The first part is a double ended needle mounted in a hub. Various types of valves have been designed for this part to operate automatically and normally for collection of successive samples in successive collection containers.
The second part, the collection container, is in the form of a partially or fully evacuated tube which may or may not contain medicament to act with the blood when it is collected in the tube. A rubber stopper is generally used to close the open end of the tube and maintain the vacuum therein. The stopper is of a self-sealing puncturable material to facilitate coupling and uncoupling of the needle assembly with the tube during use. There have been different types of stoppers developed throughout the years to assist in this coupling and uncoupling action while maintaining the vacuum prior to coupling and maintaining the integrity of the interior in the tube after sampling has been completed.
The third component of the system is generally identified as a holder and is adapted for removable attachment to the hub holding the cannula such as by threaded interengagement. The holder acts as a convenient means for holding the assembly during use and also acts as a guide for the tube so that it can easily be into alignment for penetration by the needle and also for removal of the tube and introduction of a subsequent tube as a series of samples are collected. Once again, various improvements have been developed through the years to provide better holders for better guideways, to improve the gripping surface for the operator and to form certain indicating positions to help the user determine of his relative positioning of the needle with respect to the tube.
These various improvements are designed to provide a dependable and efficient blood collection assembly of the evacuated tube type while maintaining low cost, including both the cost of manufacture and the cost of storage and ultimate use. Disposability is important in the medical instrument field today. Naturally, reduction in the number of parts reduces the total cost of the assembly and makes disposability more feasible, particularly in mass use. This is an important goal in the medical instrument field today.